1. Field of the Invention
The present invention relates to a solid modeling method which is intended to be used in a CAD (Computer-Aided Drafting) system directed to a structural object which has a component in which two-dimensional boundary geometry and the maximum and the minimum values of an existence domain in a depth (or height) direction with regard to a base plane is univocally given to the base plane and a structure which is composed of the component.
2. Background Art
A solid modeling method method has been used in CAD as a data structure for representing solid-geometry, B-reps (Boundary representation) and CSG (Constructive Solid Geometry). A complete geometric representation of an object is performed by these methods.
In the method using the B-reps, since it is important to represent accurately a three-dimensional solid geometry, the data structure is liable to become very large and complex, therefore much processing time is required in this application.
In a three-dimensional NC process in which shapes of complex curved surfaces are required to be treated with accuracy, the foregoing B-reps method is effective. However, in a field in which the shape is not so three-dimensionally complex, but an artificial intelligence (AI) is used, and a solid-like treatment is required in order that a human and a computer give the same interpretation to a figure and a meaning represented by it, the B-reps method represents too much load on the processing of the computer.
On the other hand, although the method using CSG represents an object by a set operation of primitives such as a sphere, a parallelepiped, a cone or the like, problems remain in treatment where tolerance or roughness in each side or surface of an objective primitive is different from each other, since the method for representing the geometric element of side, plane or the like composing a primitive by structural representation is not yet established. Moreover, in a CAD system having a data structure of two-dimensional and three-dimensional wire frames which are widely utilized in the market, the CSG method has not been usable.